Comparison between the Effects of Sludge and Manure Application on the Soil of a Citrus Orchard

摘要

The urban sludge is a residue originated from the wastewater treatment - the solid phase and the application as an organic fertilizer may represent an alternative to the pollution effects in nature. In an orchard of orange-trees (Citrus sinensis, L. Osbeck), the application of sludge was compared with the application of manure and with a control. Then, the chemical responses of the soil system were observed. Analyses of soil were done, to study the variation of soil salinity (ECs) and other parameters, such as the pH, organic matter (OM), N, P_2O_5, K_2O, Fe, Mn, Zn, Ca, Mg and Na. There was not any significant difference among soil nutrients content and salinity of the sludge, compared to the application of the manure and the control treatments. Hence, it was not found any inconvenient related to salinity and chemicals for the soil and for the citrus orchard with the application of the manure, and especially the urban sludge (once this fertilizer / soil amendment is available in larger amounts). So, the application of urban sludge may be a profitable alternative to the use of mineral fertilizers and to other soil amendments.